Subjective Assessment Of Inventive Step Questioned By Delhi High Court: Case Remanded For Reconsideration

In an ongoing dispute filed by Tapas Chatterjee for the rejection of a patent application for the ZLD (Zero Liquid Discharge) System by the patent office and its affirmation by the Single Judge, the Division Bench (DB) of the Delhi High Court dealt with the mechanical approach followed by the patent office while examining the patent applications.

Noting the absence of guidelines for assessing "obviousness" in the Patents Act, 1970, the Court observed that the Patent Office routinely decides patent applications or oppositions on a rule-of-thumb basis, based solely on subjective opinions. This, according to the Court, was clearly a thoroughly legally unsatisfactory position. This critical remark was made by the Division Bench of the Delhi High Court while delivering the judgment on the appeal in Tapas Chatterjee vs Assistant Controller of Patents and Designs [October 6, 2025].

The Court, in this case, questioned the subjective approach followed by the Patent Office, leading to a lack of proper reasoning for the rejection of the patent. The Court also clarified how the "Person Skilled in the Art" Test, as laid down in the 'five-step test' by this Court in F. Hoffmann-La Roche Ltd. vs Cipla Ltd, should be applied while analysing the inventive step under Section 2(1)(ja). The Court stated that the Single Judge, while affirming the rejection of the patent, had erred in applying the five-step test, particularly by failing to first identify who the skilled person was.

The Court also observed that by ignoring all the foundational steps, the Single Judge directly started the test at Step 4 of the 'Hoffman test', and this was the reason their inventive step examination was erroneous. The correct approach, according to the Court, should have been to apply all five foundational steps as enumerated in the 'Hoffman test'. The Court further observed that "while all the steps identified in Hoffmann are important, we would lay particular emphasis on Steps 1, 2 and 5' in this case. The Court found that neither the order of the AC, nor the impugned judgment of the Single Judge, contained sufficient reasons to make out a case for rejecting the subject application either under Section 3(d) or under Section 25(1)(e) read with Section 2(1)(ja) of the Patents Act. The Court directed that the office of the CGPDTM re-examine the entire issue and that a proper and reasoned order be passed.

Factual Matrix

Tapas Chatterjee filed a patent application for a new process to recover potassium sulphate from waste generated by distilleries. The application was opposed for the reason that it was not a new or inventive process. The Assistant Controller (AC) upholds the opposition to the patentability of the subject invention under Section 25(1)(e) and under Section 25(1)(f) read with Section 3(d) of the Patents Act. The AC vide order dated December 28, 2021, refused the application, stating that the claimed invention was "obvious" based on prior art, and it also fell within the exclusions under Section 3(d) of the Act as a mere use of known processes.

The applicant filed an appeal in the Delhi High Court. The Single Judge vide the judgment dated March 10, 2023, affirmed the order of rejection of the patent by AC. Both of the grounds, viz (i) the subject patent application is hit by non-patentability under Section 3(d) of the Act and (ii) lacks inventive step in terms of Section 2(1)(ja) of the Act, cited by the Assistant Controller for refusing the subject patent application under Section 15 of the Act were upheld by Single Judge. The appellant filed an appeal assailing the said decision of the single Judge.

Key issues before the Division Bench

The Division Bench was concerned only with the sustainability of the order passed by the AC and upheld by the learned Single Judge, insofar as it upholds the opposition to the patentability of the subject inventionunderSections 25(1)(e)and 25(1)(f)read withSection 3(d) of the Patents Act.

Appellant's Case

Lack of Proper Reasons

The appellant contended that there was a lack of detailed reasoning by the Assistant Controller. The appellant pointed out that, instead of providing proper reasoning, the AC merely reproduced the legal provisions and claimed the invention was obvious, without actually explaining how someone skilled in the field could have derived the process from the prior art. The appellant contended that the Assistant Controller failed to consider differences in processes and products and mechanically applied the provisions of section 3(d).

Erroneous Application of the 'Hoffman Test'

The appellant submitted that both the Assistant Controller and the Single Judge erred in applying the 'Hoffman test' for determining inventive step. The appellant explained that they neglected to identify the skilled person first. The appellant further explained that the learned Single Judge ignored all foundational steps and proceeded directly to Step 4 of the 'Hoffman test'. It was contended that this approach of determining examination of inventive step under the Hoffman test was erroneous.

Inventiveness Resides in Simplicity

The appellant contended that the claimed process was simple compared to the complicated 12-step process of D1, which involves several reagents. The reagents used were different. The appellant claimed that, in the case of D1, the final product is potassium nitrate, whereas in the appellant's process, it is potassium sulphate.

Division Bench's Analysis and Findings

On the Lack of General Guidelines on PISTA

The Court observed that there is no guidance whatsoever in the Patents Act as to how one is to assess whether a person skilled in the art, possessing the teachings of prior art and general knowledge, would or would not be able to arrive at the invention sought to be patented. This is clearly underscored by the manner in which the Assistant Controller passed the order in the present case. The Court noted that in the absence of any guidance or existing indicia based on which the aspect of obviousness of the subject invention vis-à-vis prior art is to be gleaned, from the perspective of the person skilled in the art, orders such as the present may be passed in which no explanation whatsoever is adduced for the finding that a person skilled in the art would be able to arrive at the subject invention from the teachings in the prior art.

Further, the Court noted that there may be cases in which it is not apparent, by a mere reading of the complete specifications of the prior art and the subject invention, that the latter is obvious to a person skilled in the art from the former. The Court observed that in such a case it would be incumbent on the Controller to set out, clearly and explicitly, his reasons for holding that the teachings in the prior art document would by themselves suffice to enable a person skilled in the art to arrive at the claims in the subject invention. The Court stated that in the present case, AC gave only a mere finding, unsupported by any reasons whatsoever, that the claims in the complete specification relating to the subject invention are obvious from prior art.

According to the Court, these findings have been arrived at with complete non-application of the mind. The Court noted that this was clear from the reference, in the order of the AC, to D1 alone, D2 alone, D1-D2 in combination, D3 in combination with D1 or D2, or both, D4 in combination with D1 or D2 or both and D1-D4 combined. The Court observed that there was clearly no independent application of mind to any of the individual prior arts or the effect that would arise if they were combined.

On the "Person Skilled in the Art" Test

The Court held that both the Assistant Controller and the learned Single Judge erred in applying the 'Hoffman test', particularly in failing to identify the skilled person first. The DB also observed that by ignoring all the foundational steps, they directly started the test at Step 4 of the 'Hoffman test'. The Court ruled that this approach of their examination of inventive step was erroneous. The Court stressed that determining whether an invention is obvious requires imagining what a "person skilled in the art" would think. The Court found that neither the order of the Assistant Controller, nor the impugned judgment by a single Judge, contains sufficient reasons to make out a case for rejecting the subject application either under Section 3(d) or under Section 25(1)(e) read with Section 2(1)(ja) of the Patents Act.

On Laconic findings of the Controller relating to inventive step

The DB examined the approach followed by the Controller in reaching the decision that the invention lacks inventive step. According to the Court, the Controller acknowledged that the subject invention is novel vis-à-vis prior art D1 and D2 for the reason that all features of the subject invention, as reflected in the complete specifications, were not disclosed in either D1 or D2. The Court observed that If, there were features in the subject invention which were not disclosed either in D1 or D2, and the Assistant Controller felt that in proceeding from D1 and/or D2 to the subject invention, no inventive step was involved, the AC should have identified the features of the subject invention which were not present in D1 and D2 and demonstrated how those features would not require a person skilled in the art to employ any inventive step. The Assistant Controller did not do so in this case. This, according to the Court, rendered the Assistant Controller's findings on the novelty of the subject invention vis-à-vis the prior arts D1 and D2, and on the absence of inventive step, inherently contradictory.

On the Applicability of Section 3(d)

The Court found that the Assistant Controller merely mechanically reproduced the verbatim of Section 3(d) without deeming it necessary to provide even a scintilla of an explanation, thereafter, for his decision that the subject invention is hit by Section 3(d). The Court examined the provisions of Section 3(d) in detail and observed that Section 3(d) separates the expressions "results in a new product" and "employees at least one new reactant", with the conjunction "or" and observed even if it were to be assumed that a later process, which is sought to be patented, is a mere use of an earlier known process, it would nonetheless be patentable if it either results in a new product or employees at least one new reactant.

Satisfaction of one or the other requirement. Either would suffice. Applying this interpretation to the present case means that the subject process, that the appellant desires to patent, is not rendered non-patentable by virtue of Section 3(d); firstly, because there are marked differences in the process claimed in the subject application and the processes forming subject matter of D1 and D2 and, secondly, because the process that the appellant desires to patent results in products which are not claimed outcomes of the processes envisaged in D1 and D2. The Court ruled that "the invocation ofSection 3(d), by the AC and by the learned Single Judge, is unjustified on at least two counts, viz.

(i) there is no material on the basis of which it could be said that the process forming subject matter of the Claims in the subject application is "known", or a "mere use" of the processes envisaged in D1 or D2, and

(ii) at the very least, magnesium sulphate and activated carbon are among the products which result from the process that the appellant desires to patent, and which find no mention in D1 or D2."

Division Bench's Decision

The Court ruled that, in view of the aforesaid reasons, the entire issue would have to be re-examined by the office of the CGPDTM, and a proper and reasoned order should be passed. The finding of the learned Single Judge, as also of the AC, that the process that the appellant desires to patent is obvious from the prior art documents D1 and D2 is not, therefore, in our view, supported by sufficient material to sustain it. It has, therefore, to be set aside. According to the Court, the subject process that the appellant desires to patent would ipso facto be entitled to be treated as inventive, or not obvious, vis-à-vis the prior art documents D1 and D2. The Court noted that whether the subject process satisfies this requirement would have to be determined by strictly following the tests laid down by the Division Bench in Hoffmann. The Court rejected the opposition that the subject process is not patentable because of Section 3(d) of the Patents Act.

Takeaways

This case highlights the mechanical manner in which the patent office examined the inventions for determining inventive steps. The Court was critical in categorically questioning the subjective approach followed by a patent office, leading to a lack of proper reasoning for the rejection of the patent. The Court reaffirmed the validity of Hoffman's five-step test for assessing inventive step and directed the patent office to strictly follow it. On interpretation of Section 3(d), the Court noted that even if it were to be assumed that a later process, which is sought to be patented, is a mere use of an earlier known process, it would nonetheless be patentable if it either results in a new product or employs at least one new reactant.

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